Presently, many pieces of cleaning equipment are subjected to water or moisture. Particularly, wet/dry vacuum cleaners such as those known as utility vacs and carpet extractors operate in an environment in which the debris which is extracted from the surface being cleaned is laden in a mixture of air and water. In order to prevent the moisture laden air from entering the vacuum generating motor, bypass motors are typically used in these operations. As is known to those skilled in the art, a bypass motor/fan assembly is one in which the working air, generated by a working air fan, never passes through the motor, but is totally isolated from the motor. The motor itself has a separate motor cooling air fan which draws cooling air over the motor armature and field. Accordingly, the working air and the motor cooling air take totally separate paths, and do not mix--except possibly in an exhaust area. While both the motor cooling fan and the working fan operate on the same shaft, in a bypass motor the chambers for the working air and motor cooling air are separate and distinct from each other such that moisture laden air never enters the motor.
In the past, bypass motors have typically positioned a working air fan at an end of the motor/fan shaft, with the fan rotating within a fan shell. The shell defines a chamber within which the fan operates. An end of the fan shell is provided with an air intake, with the circumference or periphery of the shell being defined by a plurality of spaced apart exhaust apertures. The intake aperture communicates with a vacuum chamber in the cleaning device, while the exhaust ports communicate with the ambient. Typically, the fan shell simply defines a chamber in which the fan rotates and, accordingly, that chamber becomes pressurized such that the air therein eventually finds its way to an exhaust port. However, with this type of a structure, the fan operation is quite inefficient and given to the generation of significant volumes of noise.
Those skilled in the art will appreciate that previously known bypass motors are highly inefficient. The pressurization of the fan chamber and the indirect exhausting of the air therefrom gives rise to inherent inefficiencies characterized by the noise generated thereby. Both are objectionable. Accordingly, there is a need in the art for a highly efficient and quiet bypass motor for use in motor/fan applications involving moisture laden air.